3.12 练习

public class zhengze  {
    
    

    public static boolean isgod(String path){
    
    

        Pattern compile = Pattern.compile( "[a-zA-Z_]{1,}[0-9]{0,}@(([a-zA-z0-9]-*){1,}\\.){1,3}[a-zA-z\\-]{1,}");

        Matcher matcher = compile.matcher(path);

        return matcher.matches();

    }
}




public class MusicUtil {
    
    

    public static List<Music> getMusic(Context context){
    
    

        List<Music> lists = new ArrayList<>();
        Uri uri = MediaStore.Audio.Media.EXTERNAL_CONTENT_URI;

        ContentResolver contentResolver = context.getContentResolver();

        Cursor cursor = contentResolver.query(uri, null, null, null, null);
        if (cursor != null){
    
    
            while (cursor.moveToNext()){
    
    

                String title = cursor.getString(cursor.getColumnIndex(MediaStore.Audio.Media.TITLE));
                String artist = cursor.getString(cursor.getColumnIndex(MediaStore.Audio.Media.ARTIST));
                String duration = cursor.getString(cursor.getColumnIndex(MediaStore.Audio.Media.DURATION));
                String data = cursor.getString(cursor.getColumnIndex(MediaStore.Audio.Media.DATA));
                String size = cursor.getString(cursor.getColumnIndex(MediaStore.Audio.Media.SIZE));
                Music music = new Music(title, artist, duration, data, size);
                lists.add(music);

            }
            cursor.close();
            return lists;
        }

        return null;
    }
}




<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.newstart">

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".Main4Activity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <activity android:name=".Main3Activity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>
</manifest>





public class MusicAdapter extends BaseAdapter {
    
    

    private List<Music> lists;
    private Context context;

    public MusicAdapter(List<Music> list, Context context) {
    
    
        this.lists = list;
        this.context = context;
    }

    @Override
    public int getCount() {
    
    
        return lists.size();
    }

    @Override
    public Object getItem(int i) {
    
    
        return lists.get(i);
    }

    @Override
    public long getItemId(int i) {
    
    
        return i;
    }

    @Override
    public View getView(int i, View view, ViewGroup viewGroup) {
    
    

        ViewHolder holder = null;
        if (view == null){
    
    
            holder = new ViewHolder();
            view = View.inflate(context, R.layout.song_layout,null);
            holder.text_artist = view.findViewById(R.id.text_artist);
            holder.text_duration = view.findViewById(R.id.text_duration);
            holder.text_title = view.findViewById(R.id.text_title);
            view.setTag(holder);
        }else {
    
    
            holder = (ViewHolder) view.getTag();
        }
        holder.text_title.setText(lists.get(i).getTitle());
        holder.text_duration.setText(lists.get(i).getDuration());
        holder.text_artist.setText(lists.get(i).getArtist());
        return view;
    }

    private class ViewHolder{
    
    
        private TextView text_title,text_artist,text_duration;
    }

}